#33512: DateTimeField auto_add_now is NUL when creating child model object
referencing parent model's object
-------------------------------------+-------------------------------------
Reporter: eeriks | Owner: nobody
Type: Bug | Status: new
Component: Database | Version: 4.0
layer (models, ORM) |
Severity: Normal | Keywords: auto_add_now
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Description:
When creating Model object which inherits from other Model which has
`DateTimeField` with `auto_add_now=True` and passing `parent_ptr_id`
value, then Django tries to update base Model by setting the auto_now_add
field to NUL (although the field is null=False)
Expected result:
ChildModel instance created with a link to ParentModel.
Code examples:
`models.py`
{{{
class ParentModel(models.Model):
created = models.DateTimeField(auto_now_add=True)
modified = models.DateTimeField(auto_now=True)
class ChildModel(SomeBaseModel):
some_field = models.CharField(max_length=12)
}}}
`manage.py shell`
{{{
from app.models import ParentModel, ChildModel
parent_object = ParentModel.objects.create() # OK
ChildModel.objects.create() # OK
ChildModel.objects.create(parentmodel_ptr=parent_object) # IntegrityError
}}}
Actual result:
Django tries to update ParentModel's `created` with NULL
{{{
UPDATE "app_parentmodel" SET "created" = NULL, "modified" = ? WHERE
"app_parentmodel"."id" = ?
}}}
And raises
{{{
django.db.utils.IntegrityError: NOT NULL constraint failed:
app_parentmodel.created
}}}
Noticed in Django 2.2, reproduced in 3.2 and 4.0. with both Postgres and
SQlite database backends.
[https://github.com/eeriks/django-demo Demo project on GitHub] to
reproduce bug.
--
Ticket URL: <https://code.djangoproject.com/ticket/33512>
Django <https://code.djangoproject.com/>
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